Method and system for combined hydrogen and electricity production using petroleum fuels

ABSTRACT

A solid oxide fuel cell (SOFC) system including a steam reformer, a hydrogen purification system, a pre-reformer, and a solid oxide fuel cell.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/730,034, filed Jun. 3, 2015, which itself is adivisional application of non-provisional U.S. patent application Ser.No. 13/683,272, filed Nov. 21, 2012, and now issued as U.S. Pat. No.9,365,131, which itself claims priority from U.S. Provisional Pat. App.No. 61/562,189, filed Nov. 21, 2011. For purposes of United Statespatent practice, this application incorporates the contents of theparent non-provisional applications and the provisional application byreference in their entirety.

BACKGROUND 1. Field

The field of invention relates to a solid oxide fuel cell (SOFC) processand system. More specifically, the field relates to using a SOFC processand system using a liquid hydrocarbon for producing electricity,hydrogen and carbon dioxide simultaneously.

2. Description of the Related Art

Liquid petroleum fractions such as naphtha, kerosene and diesel arehighly portable, widely available and can be stored at atmosphericconditions with little difficulty.

Global interest in the commercial use of non-gasoline and non-dieselpowered vehicles is accelerating. Material and design research todayfocus on both hydrogen fuel cell vehicles (HFCVs) and electricallypowered vehicles (EVs). A commonly asked question is how and where arethese vehicles fueled? Currently, hydrogen gas transport is veryexpensive on a BTU (British Thermal Unit) basis. The electricalinfrastructure and transmission lines of most countries will requiresignificant expansion and upgrade to handle the electrical demand frommobile users.

Power generation and chemical processing facilities create three majorproducts: the primary product (chemicals/electricity), steam/heat, andcarbon dioxide. Electricity/chemicals and steam/heat (generated as partof the process of heating and cooling electricity-producing processes)are useful and convertible into other forms for export, transmission orlocal usage. Carbon dioxide (and other noxious gases such as carbonmonoxide) until recently was released into the atmosphere as a wasteproduct. With more stringent greenhouse gas monitoring and reportingrequirements as well as alternative uses such as chemical production andenhanced oil recovery (EOR), it is in the generation facility's interestto not only reduce the amount of carbon dioxide produced but to captureas much as possible for use.

Purified carbon dioxide is operable to extract up to an additional 1.89barrels of crude oil per ton injected into a hydrocarbon-bearingformation as part of an enhanced oil recovery operation.

A system that not only produces electricity and hydrogen for local useas a source of portable power for vehicles but also captures carbondioxide for either sequestration or use in downstream or downholeprocesses is desirable.

SUMMARY

A method of using a SOFC system produces a refined carbon dioxideproduct, electrical power, and a compressed hydrogen product. The methodincludes the steps of introducing a hydrocarbon fuel and steam to theSOFC system. The method includes the step of operating the SOFC systemsuch that an amount of anode exhaust recycle passes into thepre-reformer such that the steam-to-carbon molar ratio in thepre-reformer is in a range of from about 3:1 to about 4:1, an amount ofoxygen passes into the reformer combustion chamber in excess of thestoichiometric amount required to fully combust all of the hydrocarbonsand hydrogen present in the reformer combustion chamber, the SOFC systemproduces a refined carbon dioxide product, electrical power, and acompressed hydrogen product, and that greater than 90% of the carbondioxide produced within the SOFC system is converted into the refinedcarbon dioxide product.

The SOFC system for producing a refined carbon dioxide product,electrical power suitable for electrically powered vehicles andcompressed hydrogen product suitable for hydrogen fuel cell vehiclesuses steam and a hydrocarbon fuel. The SOFC system includes ahydrodesulfurization system, a steam reformer having catalytic reactortubes and a reformer combustion chamber, a water-gas shift reactorsystem, a hydrogen purification system, a hydrogen compression andstorage system, a pre-reformer, a solid oxide fuel cell, an oxygengeneration system, and a CO2 purification and liquidification system. Inan embodiment of the SOFC system, the oxygen generation system of theSOFC system electrically couples to the solid oxide fuel cell andproduces both hydrogen and oxygen.

An alternative fueling station useful for fueling both electrical andhydrogen alternative fuel vehicles includes the SOFC system. Thealternative fueling station also includes an electrical conduit thatcouples to the solid oxide fuel cell of the SOFC system and is operableto convey electrical current produced by the SOFC system to anelectrical alternative fuel vehicle. The alternative fueling stationalso includes a compressed hydrogen conduit that couples to the hydrogencompression and storage system of the SOFC system and is operable toconvey compressed hydrogen having a pressure in a range of from about350 bars to about 700 bars and having a hydrogen mole purity of 99.99percent to the hydrogen alternative fuel vehicle.

A method of using an alternative fueling station to fuel an alternativefuel vehicle uses the station with the SOFC as previously described. Thealternative fuel vehicle has an alternative fuel storage device. Themethod of using the alternative fueling station includes the steps ofintroducing steam and a hydrocarbon fuel to the alternative fuelingstation and operating the alternative fueling station to produce thealternative fuel. The method includes the step of coupling thealternative fuel vehicle to the alternative fueling station such that aconduit forms between the SOFC system of the alternative fueling stationand the alternative fuel storage device. The method includes the step ofintroducing an amount of alternative fuel to the alternative fuelvehicle such that the amount does not exceed the capacity of thealternative fuel storage device. The method includes the step ofdecoupling the alternative fuel vehicle from the alternative fuelingstation.

The solid oxide fuel cell (SOFC) system and method of use produces ahighly refined, compressed hydrogen product that is useful for systemssensitive to hydrogen purity, including the fuel cells ofhydrogen-powered vehicles. The SOFC system and process also generates“surplus” electrical power. Electrical power, especially direct currentelectrical power, is useful for charging mobile battery storage systemsand exporting energy to an electrical power grid. Those of ordinaryskill in the art understand that “surplus” means an amount beyond whatis necessary to support the operation of the SOFC system during use,including the electrochemical reaction in the solid oxide fuel cell. Themethod of using the SOFC system produces a highly refined, compressedliquid carbon dioxide product useful for chemical manufacturingprocesses, enhanced oil recovery and other applications.

The SOFC system uses hydrocarbon fuels both as an energy source and as asource of reactants. The SOFC system generating both hydrogen andelectrical power proximate to a retail refueling location for HFCVs andEVs reduces the transportation infrastructure requirements and costs formoving both these products to the fueling stations. Capturing carbondioxide and forming a high quality, compressed and chilled CO2 productpermits spot marketing near potential commercial end-users or ease oftransport to remote locations for sequestration or use. Importantly, italso prevents carbon dioxide emissions to the environment.

To permit the use of different types of hydrocarbon fuels, the SOFCsystem includes both a steam reformer and a pre-reformer. The steamreformer operates to manufacture hydrogen from the steam-drivencatalytic conversion of the hydrocarbon-bearing material. Thepre-reformer converts both new and recycled streams into methane tomaximize the internal reforming capacity of the solid oxide fuel cell,which lowers its overall utility requirements and improves operationalefficiency, for converting fuel into electricity.

The inclusion of a pre-reformer in the SOFC system provides severaloperational benefits. Non-methane alkanes are more responsive toreformation into methane than methane is to converting into syngascomponents. Converting non-methane alkanes into methane stabilizes thefeed composition of the solid oxide fuel cell. In turn, compositionalfeed stability results in stabilization of operations of the solid oxidefuel cell, resulting in steady electrical and anode off-gas production.Maximizing the methane in the feed composition promotes internalreformation, which cools the interior of the fuel cell. The solid oxidefuel cell generates a significant amount of heat during conversion.Relying on the internal reforming process to support the cooling of theinterior of the solid oxide fuel cell instead of providing exteriorcooling systems saves energy and reduces the footprint—both in energyuse and size—of the system.

The inclusion of an oxygen generation system ensures that the flue gascreated in the “oxy combustor” is essentially pure carbon dioxide. Thisreduces the amount of carbon dioxide and inerts needed for purging fromthe system. The electrolysis cell provides pure oxygen in stoichiometricexcess to the carbon present in the reformer combustion chamber feeds.This ensures that nothing other than carbon dioxide forms from thecombustion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are better understood with regard to the following DetailedDescription of the Preferred Embodiments, appended Claims, andaccompanying FIGURES, where:

FIG. 1 is a process flow diagram of an embodiment of a SOFC system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Specification, which includes the Summary, Brief Description of theDrawings and the Detailed Description of the Preferred Embodiments, andthe appended Claims refer to particular features (including process ormethod steps) of the disclosure. Those of skill in the art understandthat the invention includes all possible combinations and uses ofparticular features described in the Specification. Those of skill inthe art understand that the disclosure is not limited to or by thedescription of embodiments given in the Specification. The inventivesubject matter is not restricted except only in the spirit of theSpecification and appended Claims.

Those of skill in the art also understand that the terminology used fordescribing particular embodiments does not limit the scope or breadth ofthe disclosure. In interpreting the Specification and appended Claims,all terms should be interpreted in the broadest possible mannerconsistent with the context of each term. All technical and scientificterms used in the Specification and appended Claims have the samemeaning as commonly understood by one of ordinary skill in the art towhich this invention belongs unless defined otherwise.

As used in the Specification and appended Claims, the singular forms“a”, “an”, and “the” include plural references unless the contextclearly indicates otherwise. The verb “comprises” and its conjugatedforms should be interpreted as referring to elements, components orsteps in a non-exclusive manner. The referenced elements, components orsteps may be present, utilized or combined with other elements,components or steps not expressly referenced. The verb “couple” and itsconjugated forms means to complete any type of required junction,including electrical, mechanical or fluid, to form a singular objectfrom two or more previously non-joined objects. If a first devicecouples to a second device, the connection can occur either directly orthrough a common connector. “Optionally” and its various forms meansthat the subsequently described event or circumstance may or may notoccur. The description includes instances where the event orcircumstance occurs and instances where it does not occur.

Spatial terms describe the relative position of an object or a group ofobjects relative to another object or group of objects. The spatialrelationships apply along vertical and horizontal axes. Orientation andrelational words including “upstream” and “downstream” and other liketerms are for descriptive convenience and are not limiting unlessotherwise indicated.

Where a range of values is provided in the Specification or in theappended Claims, it is understood that the interval encompasses eachintervening value between the upper limit and the lower limit as well asthe upper limit and the lower limit. The invention encompasses andbounds smaller ranges of the interval subject to any specific exclusionprovided.

Where reference is made in the Specification and appended Claims to amethod comprising two or more defined steps, the defined steps can becarried out in any order or simultaneously except where the contextexcludes that possibility.

All pressure values are understood to be gauge pressure.

FIG. 1

FIG. 1 shows a process flow diagram of an embodiment of a SOFC system.The SOFC system is operable to generate electrical power, liquefiedcarbon dioxide product suitable for EOR, and hydrogen suitable for usein HFCVs from a hydrocarbon feed. FIG. 1 is a simple diagram for ease ofdescription. Those of ordinary skill in the art understand that suchsystems are complex structures with ancillary equipment and subsystemsthat render them operable for their intended purpose.

SOFC system 100 uses vaporized liquid hydrocarbons from a source outsideof the system to provide hydrocarbons for manufacture of refinedhydrogen. Hydrocarbon feed conduit 2 introduces vaporized liquidhydrocarbons into SOFC system 100 for conversion into hydrogen suitablefor HFCVs and EOR-quality carbon dioxide. Hydrocarbon feed conduit 2couples to a liquid hydrocarbon feed storage facility that is outside ofSOFC system 100.

Hydrocarbon feed conduit 2 couples to the process inlet of hydrotreater4 and introduces a portion of the vaporized liquid hydrocarbon intohydrotreater 4. Hydrotreater 4 is operable to convert organic sulfurcompounds into hydrogen sulfides and alkanes using hydrogen over ahydrotreating catalyst, producing a hydrotreated gas. Hydrogen recyclefeed conduit 6, which couples hydrotreater 4 to H2 compression train 8,introduces a portion of compressed hydrogen into hydrotreater 4 tosupply the hydrogen for hydrotreatment. The hydrotreated gas passes fromhydrotreater 4 into sorbent bed 10. Sorbent bed 10 absorbs the hydrogensulfide from the hydrotreated gas using a metal oxide absorbent andforms desulfurized hydrocarbon gas as a product.

Although shown stacked on top of one another in FIG. 1 for artisticconvenience, those in the art understand that steam reformer 12 actuallyhas catalytic reactor tubes 14 containing reformation catalyst passingthrough combustion chamber 16. Reformer feed conduit 18 couples sorbentbed 10 to the process inlet of catalytic reactor tubes 14 and introducesthe desulfurized hydrocarbon gas into steam reformer 12. Steam reformer12 is operable to convert the alkanes in the desulfurized hydrocarbongas into a reformer syngas with steam in the presence of the reformationcatalyst. The reformer syngas predominantly is made of hydrogen, carbonoxides and water. Trace amounts of methane and inerts may also bepresent. Superheated steam conduit 20 couples to and introducessuperheated steam from a steam generation system outside of SOFC system100 into catalytic reactor tubes 14. Steam reformer 12 receives heattransferred from combustion chamber 16, which is the main thermal driverfor the reformation process occurring in catalytic reactor tubes 14.

Reformer product conduit 22 couples catalytic reactor tubes 14 of steamreformer 12 to the process inlet of water-gas shift reactor system 24and introduces the reformer syngas into water-gas shift reactor system24. Water-gas shift reactor system 24 is operable to convert carbonmonoxide and water in the reformer syngas into carbon dioxide andhydrogen, forming a shifted syngas. Water condensate conduit 26 couplesto water-gas shift reactor system 24 through a liquid outlet and passescondensed water to a water handling facility outside of SOFC system 100.

Water-reactor product conduit 28 couples water-gas shift reactor system24 to hydrogen pressure-swing absorber (PSA) 30 and introduces theshifted syngas to hydrogen PSA 30. Hydrogen PSA 30 is operable toextract hydrogen from the shifted syngas, forming a low-pressure off-gasand refined hydrogen gas. PSA off-gas conduit 32 couples to solid oxidefuel cell 34 and directs the low-pressure off-gas, which includesmethane, carbon oxides, inerts and some hydrogen to solid oxide fuelcell 34.

Product hydrogen conduit 36 couples hydrogen PSA 30 to hydrogencompression train 8 and introduces the refined hydrogen gas intohydrogen compression train 8. Electrolysis hydrogen conduit 38 coupleselectrolysis cell 40 to hydrogen compression train 8 and introduceselectrolysis hydrogen into hydrogen compression train 8. Hydrogencompression train 8 pressurizes both the refined hydrogen gas andelectrolysis hydrogen into a compressed hydrogen product suitable fortransport and use in HFCVs. Compressed hydrogen product conduit 42directs the compressed hydrogen not used for recycle to hydrotreater 4into a compressed hydrogen product storage facility outside of SOFCsystem 100.

SOFC system 100 uses vaporized liquid hydrocarbons from a source outsideof the system to provide hydrocarbons for manufacture of refinedhydrogen, carbon dioxide suitable for EOR and electricity. Hydrocarbonfeed conduit 44 couples to pre-reformer 46 and introduces vaporizedliquid hydrocarbons from the source exterior to SOFC system 100. Steamrecycle conduit 48 also couples to the process side of pre-reformer 46and introduces a portion of the anode off-gas, which includes steam,from solid oxide fuel cell 34 as a feed. Pre-reformer 46 converts thevaporized hydrocarbon feed and the anode off-gas with steam in thepresence of a pre-reformer catalyst into a pre-reformed process gas. Thepre-reformed process gas contains carbon dioxide and methane with somecarbon monoxide, hydrogen and water.

Pre-reformer product conduit 50 couples sorbent bed 52 to pre-reformer46 and introduces the pre-reformed process gas into sorbent bed 52.Sorbent bed 52 absorbs the hydrogen sulfide present in the pre-reformedprocess gas that forms in pre-reformer 46. Sorbent bed 52 forms adesulfurized process gas upon removing the hydrogen sulfide from thepre-reformed process gas.

Sorbent bed product conduit 54 couples to the outlet of sorbent bed 52.Sorbent bed product conduit 54 and PSA off-gas conduit 32 joindownstream to form anode feed conduit 56. The desulfurized process gasfrom sorbent bed 52 and the PSA off-gas from hydrogen PSA 30 mix andform an anode feed gas that contains methane, carbon oxides, hydrogenand water.

Anode feed conduit 56 couples hydrogen PSA 30 and sorbent bed 52 toanode 58 of solid oxide fuel cell 34 and introduces the anode feed gasinto anode 58. Anode 58 internally reforms the methane and watercontained in the anode feed gas into hydrogen and carbon oxides, formingan anode off-gas.

Compressed air conduit 60 couples to cathode 62 of solid oxide fuel cell34 and introduces compressed air into cathode 62 from air handlingsystems exterior to SOFC system 100. In the cathode, solid oxide fuelcell 34 uses electricity to extract oxygen ions from the compressed airin cathode 62, forming an oxygen-deficient air in cathode 62. Cathodedeficient air conduit 64 couples to cathode 62 and passes theoxygen-deficient air to air handling systems exterior to SOFC system100.

Solid oxide fuel cell 34 promotes the electrochemical reactions ofextracted oxygen anions with the hydrogen and carbon monoxide present inthe anode feed gas in anode 58 to form water and carbon dioxide. Theelectrochemical reactions free electrons, some of which are useful forcontinuing the electrochemical reaction by extracting additional oxygenions on cathode 62. Anode off-gas conduit 66 couples to anode 58 anddirects the anode off-gas towards pre-reformer 46 and combustion chamber16. Anode off-gas contains water vapor and carbon dioxide with traces ofhydrogen, methane and carbon monoxide.

Electrical conduit 68 couples to solid oxide fuel cell 34 and directsthe excess electricity produced by solid oxide fuel cell 34 to powergrid conduit 70 and electrolysis electrical conduit 72. Power gridconduit 70 directs a portion of the electricity to electricaldistribution exterior to SOFC system 100 while electrolysis electricalconduit 72 directs electrical current to electrolysis cell 40 for oxygenand hydrogen generation.

Anode off-gas conduit 66 couples the process outlet of anode 58 of solidoxide fuel cell 34 to the process inlet of both pre-reformer 46 andcombustion chamber 16 of steam reformer 12. A portion of the anodeoff-gas is recycled to pre-reformer 46 through steam recycle conduit 48because of the water content and the heat of the stream. The remaininganode off-gas is directed through reformer feed conduit 74 towardscombustion chamber 16 of steam reformer 12.

Electrolysis electrical conduit 72 couples solid oxide fuel cell 34electrically to electrolysis cell 40. Electrolysis electrical conduit 72introduces electricity to electrolysis cell 40. Electrolysis waterconduit 76 introduces water into electrolysis cell 40 from waterhandling exterior to SOFC system 100. Electrolysis cell 40 is operableto produce electrolysis hydrogen and electrolysis oxygen fromelectrically splitting water. Electrolysis hydrogen conduit 38 directsthe produced electrolysis hydrogen to hydrogen compression train 8 andelectrolysis oxygen conduit 78 directs electrolysis oxygen intocombustion chamber 16 of steam reformer 12.

SOFC system 100 uses vaporized liquid hydrocarbons from a source outsideof the system to provide hydrocarbons for combusting solid oxide fuelcell 34 off-gases into an EOR-quality carbon dioxide product and toprovide heat for catalytic reformation in catalytic reactor tubes 14 ofsteam reformer 12.

Hydrocarbon feed conduit 82 introduces vaporized liquid hydrocarbonsinto combustion chamber 16 of steam reformer 12. Combustion chamber 16is operable to form a flue gas from the combustion of the vaporizedliquid hydrocarbons and anode off-gas with the electrolysis oxygen. Theflue gas is mostly carbon dioxide with possibly minor amounts of oxygenand water.

Flue gas conduit 84 couples combustion chamber 16 to the process inletof CO2 purification system 86. Flue gas conduit 84 introduces the fluegas to CO2 purification system 86. CO2 purification system 84 isoperable to separate carbon dioxide from the flue gas and convert itinto a liquid carbon dioxide product. CO2 purification system 86 alsoproduces as part of the separation process a gas purge and water. CO2product conduit 88 directs the liquid carbon dioxide product to CO2product storage exterior to SOFC system 100. Water conduit 90 directscondensed water to water handling exterior to SOFC system 100. Gas purgeconduit 92 directs gases from the CO2 purification system pointsexterior to SOFC system 100.

Hydrocarbon Fuel

The SOFC system is operable to accept a variety of hydrocarbon fuels asboth a source of energy as well as a source for reactants available toproduce product hydrogen, carbon dioxide and electricity. Examples ofuseful hydrocarbon fuels for use in the SOFC system include natural gasand its fractions and blends thereof, including hydrogen, methane,ethane, propane, butanes, pentanes, hexanes, liquefied petroleum gas(LPG), liquefied natural gas (LNG), and natural gas liquids (NGL);natural and refined gasoline; associated gas liquid condensate;atmospheric crude oil fractions, including naphtha, especially heavynaphtha, kerosene, and gas oil; diesel fuel; post-refined pure, blendedor contaminated petrochemicals, including mixed BTEXs(benzene/toluene/ethylbenzene/xylenes); and liquid vacuum crude oilfractions. Atmospheric crude oil fractions, including naphtha, keroseneand diesel gas oil are useful hydrocarbon fuels because of theirrelative availability, portability and density. These hydrocarbon fuelsalso do not require additional cooling or heating to maintain theirstate of storage and fluid mobility.

The method of using the SOFC system includes introducing hydrocarbonfuel into the SOFC system in a non-liquid state. The method introducesthe hydrocarbon fuel as a gas, a vaporized liquid, an atomized liquid asa combination any of the three. Atomization is useful for hydrocarbonliquids having a final boiling point (FBP) greater than 170° C. to avoidcoking due to excessive heating to achieve the non-liquid state.Examples of hydrocarbon fuels that may require atomization include heavynaphtha, kerosene, diesel fuel and fuel oils. An embodiment of themethod of using the SOFC system includes introduction of the hydrocarbonfuel at a temperature of about 380° C.

An embodiment of method of use includes the introduction ofcompositionally similar hydrocarbon fuel throughout the SOFC system. Insuch an embodiment, hydrocarbon fuel is introduced into thehydrodesulfurization system, which feeds the hydrogen productionprocess, the pre-reformer, which feeds the electricity productionprocess, and the reformer combustion chamber, which feeds the carbondioxide production process. The embodiment of the SOFC system shown inFIG. 1 introduces hydrocarbon fuel from a single hydrocarbon fuelsource. An embodiment of the method of using the SOFC system includesintroducing a first hydrocarbon fuel to a part of the SOFC system and asecond hydrocarbon fuel to a different part of the SOFC system, wherethe first and second hydrocarbon fuel have different compositions. Suchan embodiment provides flexibility in operating the SOFC system tooptimize hydrogen, electricity and carbon dioxide production based upondifferent available hydrocarbon feedstocks, inventory of products,consumer demand and feedstock pricing.

Hydrodesulfurization System

Liquid hydrocarbons, especially atmospheric distilled fractions of crudeoil, contain organic sulfur compounds. Examples of heterorganic sulfurcompounds include alkane and cycloalkane sulfides, mercaptans,disulfides, polysulfides and thiophenes. Organic and inorganic sulfurcompounds poison most reformer and electrochemical catalysts. The SOFCsystem includes a hydrodesulfurization system that is operable toconvert organic sulfur compounds into hydrogen sulfide using hydrogen inthe presence of a hydrotreater catalyst. The hydrodesulfurization systemis also operable to remove the hydrogen sulfide from the process gas tosweeten it.

The hydrotreater of the hydrodesulfurization system receives hydrogenfor the conversion of organic sulfur compounds into hydrogen sulfide.The hydrogen can be purified or blended. The hydrogen can originate froma source inside or outside the SOFC system. An embodiment of the SOFCsystem includes a hydrogen recycle to the hydrotreater from a downstreampart of the SOFC system. Hydrogen-containing streams internal to theSOFC system include the off-gas and the product gas of the hydrogenpurification system, the hydrogen gas from the oxygen generation systemand the process gas treated by the water-gas shift reactor system. Anembodiment of the method of using the SOFC system includes recyclingpartially compressed product hydrogen from the hydrogen productcompressors to the hydrotreater. The hydrogen reacts with theheterorganic compounds in the presence of the hydrotreater catalyst—amolybdenum cobalt catalyst.

The SOFC system includes a sorbent bed operable to remove hydrogensulfide from the hydrotreated gas. The sorbent bed removes the hydrogensulfide using a solid metal oxide desiccant, producing a desulfurizedhydrocarbon gas. The sorbent bed contains metal oxides that absorbhydrogen sulfide. Examples of useful metal oxides include tin oxides,iron oxides and zinc oxides.

Steam Reformer

The SOFC system includes a steam reformer, which includes catalyticreactor tubes passing through a combustion chamber or furnace. Thecatalytic reactor side of the reformer is operable to converthydrocarbons into hydrogen and minor bits of methane and carbon oxides.The furnace side provides the heat for the catalytic reactor side bycombusting hydrocarbon and creating carbon dioxide. Heat from thecombustion on the furnace side radiates into the catalytic reactor tubesand promotes the cracking reactions. The steam reformer containsmultiple catalytic reactor tubes.

Reformer Catalytic Reactor Tubes

In the SOFC system, the catalytic reactor tubes couple to the sorbentbed of the hydrodesulfurization systems and receive desulfurizedhydrocarbon gas. The catalytic reactor tubes use steam reforming in thepresence of a reforming catalyst to produce a syngas with mostlyhydrogen and a little methane. Minor parts of carbon oxides are alsopresent.

The catalytic reactor tubes also receive steam, which provides water forthe reformation reactions as well as intrinsic heat since reformation isan endothermic process. The steam can be wet, dry or superheated steam.Superheated steam is useful. An embodiment of the method of using theSOFC system includes introducing superheated steam having a temperatureof about 650° C. to the catalytic reactor tubes. An embodiment of themethod of using the SOFC system includes introducing steam into thecatalytic reactor tubes at a steam-to-carbon molar feed ratio (SCR) isin a range of from about 2:1 to about 4:1. An embodiment of the methodof using the SOFC system includes introducing steam into the catalyticreactor tubes at a SCR value of about 3:1. The SCR is the molar amountof steam (as water) for every mole of carbon in the desulfurizedliquefied hydrocarbon fed to the catalytic reactor tubes.

To facilitate methanation, the catalytic reactor tubes operate in alower pressure and temperature range than normal steam reformerconditions. An embodiment of the method of using the SOFC systemincludes maintaining the temperature in the catalytic reactor tubes in arange of from about 775° C. to about 825° C. An embodiment of the methodof using the SOFC system includes maintaining the temperature in thecatalytic reactor tubes at about 800° C. An embodiment of the method ofusing the SOFC system includes maintaining the pressure in the catalyticreactor tubes in a range of from about 8 bars to about 10 bars. Anembodiment of the method of using the SOFC system includes maintainingthe pressure in the catalytic reactor tubes at about 9.7 bars.

The reforming catalyst in the catalytic reactor tubes has at least oneactive metal. The active metal reforming catalyst material is preferablycomprised of at least one Group 8-10 metal and more preferably isnickel. Nickel is preferred due to activity, low cost and readyavailability. Examples of metals useful as active metal reformingcatalysts include cobalt, lanthanum, platinum, palladium, iridium,rhodium, osmium, nickel, iron, and ruthenium. The carrier material forthe active metal reforming catalyst includes metal oxides and mixedmetal oxides (MMO). Examples of suitable carrier materials include a-and y-alumina, magnesium-aluminum oxides, cerium oxides,cerium-zirconium oxides, manganese oxides, lanthanum oxides, niobiumoxides, molybdenum oxides, calcium-aluminate, zinc oxides, siliconeoxides and titanium oxides. Although not intending to be bound bytheory, many metal oxides and mixed metal oxides are strongly suspectedof catalytic activity and are therefore operable as co-catalysts in thereformation reactions. The structure of the catalyst carrier preferablyresists thermal cycling to prevent the catalyst from being crushed.

The product reformer syngas includes hydrogen, methane, carbon oxidesand water. A series of heat exchangers can cool the syngas down to about300° C. upon passing from the catalytic reactor tubes to recapture heatand support downstream separations.

Reformer Combustion Chamber

In the SOFC system, the reformer combustion chamber couples to the solidoxide fuel cell to receive a portion of the anode off-gas. The reformercombustion chamber also receives vaporized liquid hydrocarbons as aprimary fuel. The reformer combustion chamber also couples to an oxygengeneration system that provides oxygen as a feed. The main product ofthe “oxy-combustor” is flue gas containing mostly carbon dioxide andheat. The heat from the combustion transfers into the reformer catalyticreactor tubes to support reformation.

Oxygen is a reactant in the reformer combustion chamber. The SOFC systemincludes the oxygen generation system that is operable to introduceoxygen into the reformer combustion chamber. An embodiment of the methodof using the SOFC system includes introducing oxygen in excess of thestoichiometric amount required to fully combust all of the hydrocarbonsand hydrogen introduced into the reformer combustion chamber. Anembodiment of the method of using the SOFC system includes introducingat least 10 percent more oxygen than stoichiometrically required forcomplete thermal combustion of the hydrocarbons and hydrogen introducedinto the reformer combustion chamber. Additional oxygen ensures completecombustion of the hydrocarbons and hydrogen into carbon dioxide andwater. The introduced oxygen can be blended or pure; however, air or“enriched air” is not preferred to avoid forming NOx.

An embodiment of the method of using the SOFC system includesmaintaining the operating temperature of the furnace at about 900° C. Anembodiment of the method of using the SOFC system includes maintainingat least a 90° C. temperature differential between the reformercombustion chamber and the catalytic reactor tubes to promote heattransfer.

The product flue gas is almost pure carbon dioxide. A series of heatexchangers can cool the gas passing from the reformer combustion chamberdown to about 30° C. to 50° C. to recapture heat. An embodiment of themethod of using the SOFC system includes cooling the gas passing fromthe reformer combustion chamber down to about 38° C.

Water-Gas Shift Reactor System

The SOFC system includes a water-gas shift reactor system that isoperable to convert most of the carbon monoxide present in the reformersyngas using water into carbon dioxide and hydrogen in the presence of awater-gas shift catalyst. The reformer syngas has a small amount ofcarbon monoxide that requires conversion into carbon dioxide. Inaddition, the water-gas shift reactor system creates product hydrogen.The water-gas shift reactor system produces a shifted syngas product. Anembodiment of the method of using the SOFC system includes operating thewater-gas shift reactor system such that the overall conversion ofcarbon monoxide in the reformed syngas into carbon dioxide is about 96%.

The SOFC system uses a dual-stage water-gas shift reactor system: afirst stage that is a high temperature shift (HTS) reactor and a secondstage that is a low temperature shift (LTS) reactor. The HTS reactoroperates to convert some of the carbon monoxide and water in thereformer syngas into carbon dioxide and hydrogen, forming a partiallyshifted reformer syngas. An embodiment of the SOFC process includesoperating the HTS reactor such that it maintains a temperature of about300° C. An embodiment of the method of using the SOFC system includesoperating the HTS reactor such that about 75% of the carbon monoxideintroduced with the reformer syngas converts into carbon dioxide. Anembodiment of the method of using the SOFC system includes operating theHTS adiabatically.

The HTS reactor passes the partially shifted reformer syngas into theLTS reactor. The LTS reactor also operates to convert some of the carbonmonoxide and water in the reformer syngas into carbon dioxide andhydrogen. The product from the LTS reactor is a shifted reformer syngasonly a minor amount of carbon monoxide present. An embodiment of themethod of using the SOFC system includes cooling the partially shiftedreformer syngas to a temperature in a range of from about 200° C. toabout 230° C. before introduction into the LTS reactor. An embodiment ofthe method of using the SOFC system includes cooling the partiallyshifted reformer syngas to a temperature to about 216° C. An embodimentof the method of using the SOFC system includes operating the LTSreactor such that about 80% of the carbon monoxide introduced with thepartially shifted reformer syngas converts into carbon dioxide.

An embodiment of the method of using the SOFC system includes coolingthe shifted reformer syngas to a temperature in a range of from about30° C. to about 50° C.

Hydrogen Purification System

The SOFC system includes a hydrogen purification system that couples tothe LTS reactor of the water-gas shift system. The hydrogen purificationsystem is operable to separate hydrogen from the introduced shiftedreformer gas, forming a purified hydrogen gas and an off-gas. Anembodiment of the method of using the SOFC system includes forming thepurified hydrogen gas with a hydrogen purity in a range of from about99.50 to about 99.99 mole percent. An embodiment of the method of usingthe SOFC system includes forming the purified hydrogen gas with ahydrogen purity of about 99.99 mole percent. An embodiment of the methodof using the SOFC system includes forming a purified hydrogen gas with apressure in a range of from about 5 to about 10 bars pressure. Anembodiment of the method of using the SOFC system includes forming apurified hydrogen gas with a pressure of about 7 bars pressure. Anembodiment of the method of using the SOFC system includes forming anoff-gas with a pressure in a range of from about 0.4 bars to about 1.0bars. An embodiment of the method of using the SOFC system includesforming an off-gas with a pressure of about 0.4 bars. The hydrogenpurification system off-gas includes carbon monoxide, carbon dioxide,methane, water and hydrogen.

The hydrogen purification system can separate the shifted reformersyngas using a number of technologies well known in the chemicalprocessing industry, including cryogenic liquidification, wet scrubbing(for example, Benfield process) with post-scrubbing methanation,selective membrane separation and pressure-swing-absorption (PSA)systems. An embodiment of the SOFC system includes a PSA that isoperable to purify hydrogen. The hydrogen purification system passespurified hydrogen to the hydrogen compressor system. The hydrogenpurification system directs the off-gas to the solid oxide fuel cell forelectricity production.

Hydrogen Compression and Storage System

The SOFC system includes a hydrogen compressor and storage system. Thehydrogen compressor and storage system couples to the hydrogenpurification system, receives purified hydrogen and is operable tocompress and store the product hydrogen as a compressed hydrogen productsuitable for end-use, including transport, long-term storage at lowtemperatures and for fueling HFCVs.

In the SOFC process, the hydrogen compression and storage system uses afirst compression system to pressurize the purified hydrogen to about170 bars for bulk hydrogen storage. Using a second compressor system,the hydrogen compression and storage system pressurizes the purifiedhydrogen to about 430 bars for cascade storage. At cascade storagepressure, the compressed hydrogen product is useful for dispensing in aretail manner to HFCVs. Dispensing pressures are in a range fromslightly lower (about 350 bars) to significantly higher (about 700 bars)than cascade storage pressure given the needs of the hydrogen-dispensingretail market. The various compression technologies useful forpressurizing hydrogen to these service and storage pressures are knownto those of skill in the art and include single and multi-stagecompressors, intercoolers and mist eliminators.

An embodiment of the SOFC system includes the hydrogen compression andstorage system coupling to and operable to pass a portion of compressedhydrogen product to the hydrotreatment system. An embodiment of themethod of using the SOFC system includes passing compressed hydrogenproduct to the hydrotreatment system at a pressure of about the bulkhydrogen storage pressure.

An embodiment of the SOFC system includes the hydrogen compression andstorage system coupling to the oxygen generation system. In such anembodiment, the hydrogen compressor system is operable to receivepurified hydrogen passing from the oxygen generation system. Thehydrogen compressor system acts to mix and pressurize the purifiedhydrogen from the oxygen generation system along with the purifiedhydrogen from the reformer into the compressed hydrogen product.

Pre-Reformer

The SOFC system includes a pre-reformer. The pre-reformer is operable toconvert non-methane hydrocarbons in an introduced feed into amethane-rich effluent. The methane-rich effluent is useful for adownstream SOFC to internally reform and then electrochemically convertinto carbon oxides, which generates electricity.

In the SOFC system the pre-reformer receives vaporized liquidhydrocarbons. An embodiment of the SOFC process includes introducingvaporized liquid hydrocarbons composition into the pre-reformer havingthe same liquid hydrocarbons composition as those introduced into thehydrodesulfurization system. The pre-reformer is operable to convert thenon-methane hydrocarbons introduced with the vaporized liquidhydrocarbons using water vapor and in the presence of a pre-reformercatalyst into a pre-reformer syngas product containing methane andcarbon oxides.

In the SOFC system, the pre-reformer couples to the anode outlet of theSOFC. The pre-reformer is operable to receive a portion of the solidoxide fuel cell anode off-gas as an anode exhaust recycle stream. Theanode off-gas includes significant portions of carbon dioxide and watervapor as well as some amounts of methane, hydrogen and carbon monoxide.An embodiment of the method of using the SOFC system includesintroducing the anode exhaust recycle to the pre-reformer such that asteam-to-carbon molar ratio is in a range of from about 3:1 to about4:1. An embodiment of the method of using the SOFC system includesintroducing the anode exhaust recycle to the pre-reformer such that asteam-to-carbon molar ratio is at a ratio of 3.5:1. The “steam” is molarwater (in vapor form) in the SOFC anode off-gas. The “fresh carbon” isthe molar carbon in the introduced vaporized liquid hydrocarbons.Because the SOFC anode off-gas includes a significant amount of watervapor that is already heated, the pre-reformer of the SOFC system canoperate such that “fresh” or “make-up” steam is not required as a feed.An embodiment of the method of using the SOFC system introduces steam tothe pre-reformer such that the steam-to-carbon molar ratio is in a rangeof from about 3:1 to about 4:1.

An embodiment of the method of using the SOFC system includes operatingthe pre-reformer adiabatically. An embodiment of the method of using theSOFC system includes operating the pre-reformer at a temperature in arange of from about 350° C. to about 400° C. An embodiment of the methodof using the SOFC system includes operating the pre-reformer at apressure in a range of about 9 bars.

The reforming process that occurs in the pre-reformer occurs in thepresence of a pre-reforming catalyst. An embodiment of the SOFC systemincludes a pre-reformer containing a precious active metal catalyst thatis sulfur-tolerant. Precious metals include platinum, palladium,iridium, rhodium, ruthenium, silver and gold. The pre-reforming catalystcan also include materials that improve their selectivity and reformingactivity, including samaria-doped ceria (SDC), gadolinia-doped ceria andyttria-doped ceria. In the presence of the pre-reforming catalyst,heterorganic compounds, including previously discussed organic sulfurcompounds, convert into alkanes and hydrogen sulfide. The alkanesfurther convert into methane and carbon oxides before egressing from thepre-reformer as part of the pre-reformer syngas product.

The pre-reformer syngas product is a mixture of methane and carbonoxides for use in the SOFC for electricity production. An embodiment ofthe method of using the SOFC system includes operating the pre-reformersuch that it produces the pre-reformer syngas product having methane ina range of from about 15 percent to about 20 percent on a dry molebasis. An embodiment of the method of using the SOFC system includesoperating the pre-reformer such that it produces the pre-reformer syngasproduct having methane of about 17 percent on a dry mole basis. Theremainder of the pre-reformer syngas product is predominantly hydrogenand carbon oxides.

Pre-SOFC Sorbent Bed

The SOFC system includes a sorbent bed that is operable to removehydrogen sulfide from the pre-reformer syngas product. Removing thehydrogen sulfide from the pre-reformer syngas product protects theceramic electrolyte and the reforming catalyst in the solid oxide fuelcell. The sorbent bed couples to the outlet of the pre-reformer andreceives the pre-reformer syngas. The sorbent bed contains metal oxidesthat absorb hydrogen sulfide. Example metal oxides include tin oxides,iron oxides and zinc oxides. The sorbent bed produces a desulfurizedpre-reformer syngas.

Solid Oxide Fuel Cell

The SOFC system includes a solid oxide fuel cell having a ceramicelectrolyte that couples the anode and the cathode sides. The anode sideof the SOFC is operable to internally reform methane and water in thepresence of a reforming catalyst into carbon monoxide and hydrogen, andthen electrochemically convert the formed syngas with oxygen anions intocarbon dioxide and water, producing free electrons. The cathode side isoperable to use free electrons to convert oxygen into oxygen anions. Theoxygen ions transport through the ceramic, ion-conducting electrolytefrom the cathode side to the anode side and react with the syngas on theelectrolyte surface. Excess electrical power produced by the solid oxidefuel cell is a product of the SOFC process.

In SOFC systems, the anode of the solid oxide fuel cell couples to boththe off-gas side of the hydrogen purification system and the outlet ofthe sorbent bed that couples to the pre-reformer. The two outlet streamscombine and form an anode feed stream that contains methane, hydrogen,carbon oxides and water. An embodiment of the method of using the SOFCsystem includes pre-heating the anode feed stream to about 600° C.before introduction into the anode. An embodiment of the method of usingthe SOFC system includes pre-heating the anode feed stream with thesolid oxide fuel cell anode off-gas.

Maximizing the methane composition and minimizing the amount ofnon-methane alkanes and hydrogen in the anode feed stream increases theinternal reforming capacity of the solid oxide fuel cell and improveselectricity generation. Internal reformation occurs in the presence of areforming catalyst in the solid oxide fuel cell. Internal reformationlowers the amount of compressed air used on the cathode side to cool theceramic electrolyte of the solid oxide fuel cell as the endothermicreformation reaction cools the exothermic electrochemical conversion ofsyngas into off-gas. An embodiment of the method of using the SOFCsystem includes operating the anode side of the solid oxide fuel cell ata temperature in a range of from about 500° C. to about 1000° C. Anembodiment of the method of using the SOFC system includes operating theanode side of the solid oxide fuel cell at a temperature in a range offrom about 725° C. to about 775° C. An embodiment of the method of usingthe SOFC system includes operating the anode side of the solid oxidefuel cell at a temperature in a range of about 750° C.

In SOFC systems, the anode couples to both the pre-reformer inlet andthe reformer combustion chamber. The product anode off-gas is rich incarbon dioxide and water but also has some hydrogen, carbon monoxide,water and methane. An embodiment of the method of using the SOFC systemincludes cooling a portion of the anode off-gas to a temperature of lessthan 150° C. and compressing it to a pressure of about 1.2 bars. Anembodiment of the method of using the SOFC system includes cooling aportion of the anode off-gas to a temperature of about 93° C. Cooled,pressurized anode off-gas is useful as a feed for the pre-reformer forits water, hydrogen and methane content.

The cathode side of the solid oxide fuel cell receives air driven by anair blower to supply oxygen necessary for the electrochemical conversionof the syngas on the anode side and to cool the ceramic electrolyte. Anembodiment of the method of using the SOFC system includes introducingthe feed air into the cathode side of the solid oxide fuel cell at apressure of about 0.7 bars. Pre-heating the feed air improves oxygenreduction into oxygen anions. An embodiment of the SOFC process includespreheating the feed air to a temperature of about 600° C. beforeintroduction into the cathode. An embodiment of the method of using theSOFC system includes pre-heating the feed air with the oxygen-depletedcathode side discharge.

The solid oxide fuel cell produces power in excess of SOFC processconsumption requirements. The solid oxide fuel cell system directsexcess electrical power, that is, electricity not used by the solidoxide fuel cell or other internal SOFC system users, to externaldistribution systems. An embodiment of the SOFC system includes wherethe solid oxide fuel cell electrically couples to the oxygen generationsystem and is operable to pass an electrical current to the oxygengeneration system. In such an embodiment, the electrical output from thesolid oxide fuel cell supports the oxygen-generation process in theoxygen generation system. External distribution systems include retaildistribution systems operable to provide electricity to EVs.

Oxygen Generation System

The SOFC system includes an oxygen generation system. The oxygengeneration system is operable to produce and then introduce oxygen intothe SOFC system. The oxygen generation system can use a number oftechnologies well known in the chemical processing industry to form anddistribute oxygen, including electrolysis cell, cryogenic airseparation, oxygen-selective transport membrane separation, vacuum PSA(VPSA) unit separation and ozone generator technologies.

The oxygen generation system in the SOFC system couples to the reformercombustion chamber and passes oxygen into the reformer combustionchamber as a feed. The oxygen can enter as a pure feed or as a blend. Anembodiment of the method of using the SOFC system includes operating theoxygen generation system such that it produces oxygen with a purity ofat least 80 percent oxygen on a dry molar basis. An embodiment of themethod of using the SOFC system includes operating the oxygen generationsystem such that it produces oxygen with a purity of at least 90 percentoxygen on a dry molar basis. An embodiment of the method of using theSOFC system includes operating the oxygen generation system such that itproduces oxygen with a purity of at least 95 percent oxygen on a drymolar basis.

An embodiment of the SOFC system includes an electrolysis cell as theoxygen generating system that is operable for producing electrolysisoxygen and electrolysis hydrogen using water. In such an embodiment, theelectrolysis cell is operable to use electricity to decompose water intoseparate oxygen and hydrogen products. An example of such anelectrolysis cell is a proton electrolyte membrane (PEM) electrolysiscell, which is capable of generating highly pure hydrogen (99.99 molepercent) and oxygen. In such an embodiment of the SOFC system, theoxygen generating system couples to both the reformer combustion chamberand the hydrogen compression system, where the electrolysis oxygenpasses to the reformer combustion chamber and the electrolysis hydrogenpasses to the hydrogen compressor system. The electrolysis hydrogen mayrequire pre-compression to elevate its pressure before introduction tothe hydrogen compressor system.

The oxygen generation system can use electrical power to convert feedsinto oxygen for use in the SOFC system. An embodiment of the SOFC systemincludes electrically coupling the solid oxide fuel cell to the oxygengeneration system such that electricity from the solid oxide fuel cellfosters the oxygen-generation reaction in the oxygen generation system.

An embodiment of the method of using the SOFC system includesmaintaining the temperature of the oxygen generation system at atemperature of about 50° C. during oxygen generation.

CO2 Purification and Liquidification System

The SOFC system includes a CO2 purification and liquidification system.The CO2 purification and liquidification system is operable to receivethe cooled flue gas from the reformer combustion chamber and separatelyextract water and oxygen from the cooled flue gas, forming a refinedcarbon dioxide gas. An embodiment of the method of using the SOFC systemincludes forming a refined carbon dioxide with an oxygen concentrationof less than 10 parts-per-million (ppm) molar.

The CO2 purification and liquidification system is also operable torefrigerate and compress the refined carbon dioxide gas to form a liquidcarbon dioxide product. An embodiment of the method of using the SOFCsystem includes forming a liquid carbon dioxide product with atemperature in a range of from about −20° C. to about −50° C. and apressure of about 22 bars. Suitable compression and refrigerationtechnology for liquefying refined carbon dioxide includes propanechillers.

The SOFC process and system are very efficient in containing andrecovering produced carbon dioxide for use in chemical production, EORprocesses or sequestration. An embodiment of the method of using theSOFC system includes operating the system such that over 90 percent ofall the carbon dioxide produced in the SOFC system is captured andconverted into the liquid carbon dioxide product. The SOFC processpurges the remaining carbon dioxide and inerts.

Alternative Fueling Station for HFCVs and EVs

The alternative fueling station uses a SOFC system as previouslydescribed to generate a supply of compressed hydrogen and directelectrical current, which are alternative fuels. The alternative fuelingstation is operable to distribute compressed hydrogen and directelectrical current to fuel alternative fuel vehicles, including hydrogenfuel cell vehicles (HFCVs) and electric vehicles (EVs). The alternativefueling station includes at least one conduit operable to couple to andconvey compressed hydrogen into a HFCV to fuel it. The alternativefueling station also includes at least one conduit operable to couple toand convey electrical power into an EV to charge it. The alternativefueling station is operable to fuel both HFCVs and EVs simultaneously.

The method of using the alternative fueling station to refuel analternative fuel vehicle with alternative fuels includes the steps ofintroducing hydrocarbon fuel into the SOFC system and operating the SOFCsystem to produce the alternative fuels. An embodiment of the methodincludes producing compressed hydrogen having a pressure in a range offrom about 350 bars to about 700 bars and having a hydrogen mole purityof 99.99 percent. An embodiment of the method includes producingelectricity having a direct current. An alternative fuel vehicleincludes a HFCV having a hydrogen fuel tank as an alternative fuelstorage device. An alternative fuel vehicle includes an EV with abattery bank as an alternative fuel storage device. The method alsoincludes the step of coupling the alternative fuel vehicle to the SOFCsystem such that a conduit forms between the SOFC system and thealternative fuel storage device. The method also includes the step ofintroducing an amount of alternative fuel to the alternative fuelvehicle such that the amount introduced does not exceed the capacity ofthe alternative fuel storage device. The method also includes the stepof decoupling the alternative fuel vehicle from the SOFC system.

During periods of non-use of the retail refueling station, the SOFCprocess continues to draw hydrocarbon fuel and manufacture hydrogen forlong-term storage and electricity for distribution either into a coupledelectrical grid or a spot-demand electricity storage systems, includingtraditional banks of capacitors/batteries or alternative storage means(for example, gas compression/decompression with electrically-coupledgenerators and turbines). Transmission of electricity into a coupledelectrical grid may require conversion of the electrical current fromdirect current into alternating current (AC). The continuous productionof hydrogen and electricity permits steady state operation of the SOFCsystem, which enhances reliability, troubleshooting and permits the SOFCsystem to handle sudden changes in production or demand levels over aprocess that is more “on/off” in operation.

Supporting Equipment

Embodiments include many additional standard components or equipmentthat enables and makes operable the described apparatus, process, methodand system. Examples of such standard equipment known to one of ordinaryskill in the art includes heat exchanges, pumps, blowers, reboilers,steam generation, condensate handling, membranes, single and multi-stagecompressors, separation and fractionation equipment, valves, switches,controllers and pressure-, temperature-, level- and flow-sensingdevices.

Operation, control and performance of portions of or entire steps of aprocess or method can occur through human interaction, pre-programmedcomputer control and response systems, or combinations thereof.

Examples of specific embodiments facilitate a better understanding ofsolid oxide fuel cell system and process. In no way should the Examplelimit or define the scope of the invention.

EXAMPLE

The embodiment of the SOFC system shown in FIG. 1 is configured inAspenPlus® (Aspen Technology, Inc.; Burlington, Mass.), a chemicalprocess simulator, runs two different types of vaporized liquidhydrocarbon feed stocks: naphtha and kerosene. Process simulation usingthe SOFC system shown in FIG. 1 produces 250 Nm3/hr of hydrogen suitablefor use in HFCVs (+99.99 molar percent purity) as well as provide atleast 370 kW of electrical power for EVs. Table 1 gives the results ofthe simulations.

TABLE 1 FIG. 1 simulation results for naphtha and kerosene hydrocarbonfuel. FIG. 1 Co-production Study Units Naphtha Kerosene Fuel BalanceTotal Fuel Introduced kg/hr 218.6 218.8 Total Fuel Introduced (HHV)GJ/hr 10 10.1 H2 Balance Gross Generation Nm3/hr 265 264 Consumption: ToDesulfurizer Nm3/hr 2 2 To Reformer Furnace Nm3/hr 13 13 Total H2Internal Consumption Nm3/hr 15 14 Net H2 for Export Nm3/hr 250 250 CO2Captured kg/hr 619.9 620.5 Power Balance Gross Generation kW 1272 1270Total Auxiliary Power Consumption kW 902 899 Net Export Power kW 370 371Overall Efficiency % HHV 45.3 44.7

The results of Table 1 show a High Heating Value (HHV) efficiency thatreflects a significant advantage over traditional hydrogen carrier-basedrefueling stations, which have efficiencies in the 23-25% HHV range. Theco-production of electricity by the solid oxide fuel cell as well asinternally reforming methane in the solid oxide fuel cell providessignificant energy savings reflected in the overall efficiency value.

What is claimed is:
 1. A solid oxide fuel cell (SOFC) system comprising:a steam reformer, the steam reformer comprising: catalytic reactortubes, where the catalytic reactor tubes are operable to receive steamand a hydrocarbon feed and are operable to convert hydrocarbons of thehydrocarbon feed into hydrogen to produce a reformer syngas, thereformer syngas comprising hydrogen; and a combustion chamber, where thecombustion chamber is thermally coupled to the catalytic reactor tubes,is operable to receive the hydrocarbon feed, an oxygen feed, and ananode exhaust gas, and is operable to produce a flue gas, the flue gascomprising carbon dioxide; a hydrogen purification system, where thehydrogen purification system is operable to receive the reformer syngasand is operable to produce a purified hydrogen gas and an off-gasstream, the off-gas stream comprising methane; a pre-reformer, where thepre-reformer is operable to receive the hydrocarbon feed and the anodeexhaust gas and is operable to produce a pre-reformer syngas, thepre-reformer syngas comprising methane; and a solid oxide fuel cell,where the solid oxide fuel cell is operable to electrochemically convertmethane and water into hydrogen and carbon oxides to produce electricalpower and where the solid oxide fuel cell comprises an anode side, wherethe anode side is operable to produce the anode exhaust gas, the anodeexhaust gas comprising hydrogen and carbon oxides, and comprises ananode side inlet, where the anode side inlet is fluidly coupled to thehydrogen purification system and the pre-reformer and is operable toreceive an anode feed, the anode feed comprising a mixture of theoff-gas stream and the pre-reformer syngas.
 2. The SOFC system of claim1, further comprising: an oxygen generation system, the oxygengeneration system comprising an electrolysis cell, where theelectrolysis cell is operable to receive water, is electrically coupledto the solid oxide fuel cell to receive electrical power, is operable toconvert water into hydrogen and oxygen to produce an electrolysishydrogen and an electrolysis oxygen, and is fluidly coupled to thecombustion chamber such that the oxygen feed comprises the electrolysisoxygen.
 3. The SOFC system of claim 2, further comprising: a hydrogencompression train, where the hydrogen compression train is operable toreceive the purified hydrogen gas and the electrolysis hydrogen and isoperable to produce a hydrogen recycle feed and a compressed hydrogenproduct.
 4. The SOFC system of claim 3, further comprising: ahydrodesulfurization system, the hydrodesulfurization system comprising:a hydrotreater, where the hydrotreater is fluidly coupled to thehydrogen compression train, is operable to receive the hydrocarbon feedand the hydrogen recycle feed, and is operable to convert organic sulfurcompounds in the hydrocarbon feed into hydrogen sulfide to produce ahydrotreated gas; and a first sorbent bed, where the first sorbent bedis fluidly coupled to the hydrotreater and the steam reformer, isoperable to receive the hydrotreated gas, and is operable to absorbhydrogen sulfide of the hydrotreated gas.
 5. The SOFC system of claim 1,further comprising: a water-gas shift reactor system, where thewater-gas shift reactor system is fluidly coupled to the catalyticreactor tubes and the hydrogen purification system, is operable toreceive the reformer syngas, and is operable to convert carbon monoxideand water into carbon dioxide and hydrogen.
 6. The SOFC system of claim1, where the pre-reformer is followed by a second sorbent bed, where thesecond sorbent bed is operable to receive the pre-reformer syngas and isoperable to absorb hydrogen sulfide of the pre-reformer syngas.
 7. TheSOFC system of claim 1, where the hydrogen purification system comprisesa pressure-swing-adsorption unit.
 8. The SOFC system of claim 1, wherethe pre-reformer is configured to operate adiabatically.
 9. The SOFCsystem of claim 1, further comprising: a carbon dioxide purificationsystem, where the carbon dioxide purification system is fluidly coupledto the combustion chamber, is operable to receive the flue gas, and isoperable to produce a refined carbon dioxide product.
 10. The SOFCsystem of claim 1, where the solid oxide fuel cell further comprises acathode side, where the cathode side is operable to receive an air feed,the air feed comprising oxygen, and is operable to produce oxygen ionsand an oxygen-deficient air.
 11. The SOFC system of claim 2, where theelectrolysis cell comprises a proton exchange membrane.
 12. A method ofproducing hydrogen, carbon dioxide, and electrical power utilizing asolid oxide fuel cell (SOFC) system comprising the steps of: introducinga hydrocarbon feed and steam to a steam reformer, the steam reformercomprising: catalytic reactor tubes, where the catalytic reactor tubesare operable to receive steam and the hydrocarbon feed and are operableto convert hydrocarbons of the hydrocarbon feed into hydrogen to producea reformer syngas, the reformer syngas comprising hydrogen; and acombustion chamber, where the combustion chamber is thermally coupled tothe catalytic reactor tubes, is operable to receive the hydrocarbonfeed, an oxygen feed, and an anode exhaust gas, and is operable toproduce a flue gas, the flue gas comprising carbon dioxide; introducingthe oxygen feed to the combustion chamber; introducing the anode exhaustgas to the combustion chamber; introducing the reformer syngas to ahydrogen purification system, where the hydrogen purification system isoperable to produce a purified hydrogen gas and an off-gas stream, theoff-gas stream comprising methane; introducing the hydrocarbon feed to apre-reformer, where the pre-reformer is operable to receive the anodeexhaust gas and is operable to produce a pre-reformer syngas, thepre-reformer syngas comprising methane; introducing the anode exhaustgas to the pre-reformer; and introducing an anode feed to a solid oxidefuel cell, the anode feed comprising a mixture of the off-gas stream andthe pre-reformer syngas, where the solid oxide fuel cell is operable toelectrochemically convert methane and water into hydrogen and carbonoxides to produce electrical power and comprises an anode side, wherethe anode side is operable to produce the anode exhaust gas, the anodeexhaust gas comprising hydrogen and carbon oxides, and comprises ananode side inlet, where the anode side inlet is fluidly coupled to thehydrogen purification system and the pre-reformer and is operable toreceive the anode feed.
 13. The method of claim 12, further comprisingthe step of: introducing water and electrical power to an oxygengeneration system, the oxygen generation system comprising anelectrolysis cell, where the electrolysis cell is operable to receivewater, is electrically coupled to the solid oxide fuel cell to receiveelectrical power, is operable to convert water into hydrogen and oxygento produce an electrolysis hydrogen and an electrolysis oxygen, and isfluidly coupled to the combustion chamber such that the oxygen feedcomprises the electrolysis oxygen.
 14. The method of claim 13, furthercomprising the step of: introducing the purified hydrogen gas and theelectrolysis hydrogen to a hydrogen compression train, where thehydrogen compression train is operable to produce a hydrogen recyclefeed and a compressed hydrogen product.
 15. The method of claim 14,further comprising the step of: introducing the hydrocarbon feed and thehydrogen recycle feed to a hydrodesulfurization system, thehydrodesulfurization system comprising: a hydrotreater, where thehydrotreater is fluidly coupled to the steam reformer and the hydrogencompression train, is operable to receive the hydrocarbon feed and thehydrogen recycle feed, and is operable to convert organic sulfurcompounds in the hydrocarbon feed into hydrogen sulfide to produce ahydrotreated gas; and a first sorbent bed, where the first sorbent bedis fluidly coupled to the hydrotreater and the steam reformer, isoperable to receive the hydrotreated gas, and is operable to absorbhydrogen sulfide of the hydrotreated gas.
 16. The method of claim 12,where the step of introducing the reformer syngas to a hydrogenpurification system further comprises a water-gas shift reactor system,where the water-gas shift reactor system is fluidly coupled to thecatalytic reactor tubes and the hydrogen purification system, isoperable to receive the reformer syngas, and is operable to convertcarbon monoxide and water into carbon dioxide and hydrogen.
 17. Themethod of claim 12, where the step of introducing the hydrocarbon feedto a pre-reformer further comprises a second sorbent bed, where thesecond sorbent bed is fluidly coupled to the pre-reformer and the anodeside, is operable to receive the pre-reformer syngas, and is operable toabsorb hydrogen sulfide of the pre-reformer syngas.
 18. The method ofclaim 12, where the hydrogen purification system comprises apressure-swing-adsorption unit.
 19. The method of claim 12, where thepre-reformer is configured to operate adiabatically.
 20. The method ofclaim 12, further comprising the step of: introducing the flue gas to acarbon dioxide purification system, where the carbon dioxidepurification system is fluidly coupled to the combustion chamber and isoperable to produce a refined carbon dioxide product.
 21. The method ofclaim 12, further comprising the step of: introducing an air feed to acathode side of the solid oxide fuel cell, the air feed comprisingoxygen, where the cathode side is operable to produce oxygen ions and anoxygen-deficient air.
 22. The method of claim 13, where the electrolysiscell comprises a proton exchange membrane.